Alcator C-Mod Weekly Highlights January 26, 2009 FY2009 weeks of research operations: Target: TBD Completed: 0 weeks Operations ---------- Installation of the lower arm to TF core spring-plates was completed last week. The spring-plates are installed using an hydraulic tool that measures and records the force as a function of insertion distance into the slot. Borescope inspections of the slots have also been performed. The last of the vacuum vessel heaters have been fabricated by the vendor and are being shipped. We have received the alternator rotor UT data files, which have also been sent to the vendors performing the analysis. We are making plans to take ring samples from the rotor core. The vendor contracted for this work has successfully cut a ring sample from a prototype rotor section made of steel similar to that of the MIT alternator rotor. Pending a review of this process, and the prototype results, we expect the vendor to arrive on-site within a few days. Lower Hybrid System ------------------- We continued fabrication of components for the 4-way splitters needed for the 2nd launcher. Details of the new rf probe design have been finalized. These probes will be installed in the forward waveguide section of the coupler. Design of the hardware needed to interface the probe signals to the CPS (coupler protection system) have begun. We continued testing the new CPS control and digitizer boards. An automatic threshold generation script has been developed that identifies individual channel ranges, copies the calibration data from the boards for each channel, and then computes accurate threshold values in terms of digitizer counts. ICRF Systems ------------ We have begun preparations for installation of the components needed to feed IPA (intermediate power amplifier) power into a dummy load. The dummy load will allow testing of the IPA stage independently of the following transmitter stages. Diagnostics ----------- To determine whether the DNB grids are suffering thermal deformation during long beam pulses, time-dependent thermal footprints for the beam were acquired during December. Last week, Igor Bespamyatov, UT-FRC, began the analysis of the temporally resolved evolution of the beam target surface temperature. An analytical model for heat transport in the flange was developed to account for the effects of temperature equilibration within the flange and water cooling of the flange. Internal equilibration occurs on a faster time scale than water cooling of the flange, as expected. Igor Bespamyatnov, Ken Liao, and Bill Rowan, UT-FRC, continued work on an upgrade to the BES diagnostic that will provide an alternative means for acquiring the DNB density in the plasma. The remaining lenses were ordered for the splitter, the unit that will divide the plasma emission into two components -- one for CXRS and one for BES. Simple tests using the sample lens that arrived last week indicate that the total transmission of the splitter will be greater than 85%. This transmission is acceptable for both the BES and the CXRS diagnostics. A new vendor was identified for lens mounts, and these components were ordered. Perry Phillips, UT-FRC, continued assembly of the new shielded box for the FRC-ECE diagnostic. As soon as interconnect coax cables arrive the system will be ready for installation at C-Mod. Travel and Visits ----------------- Bruce Lipschultz attended the FOM/Rijnhuizen laboratory advisory committee meeting January 12-13 in Utrecht, Holland. The lab is home to many areas of research including fusion diagnostics and modeling, plasma-surface interactions, far infrared sources and molecular physics, and UV mirror development. Following that meeting Bruce Lipschultz traveled to JET (January 14-16) for a series of discussions on activities associated with ITPA. The topics included the current JET and MAST programs, the status and plans for the 'JET ITER-like wall', and Atomic physics modeling by Hugh Summers' ADAS (Atomic Data and Analysis Structure) group. Stewart Zweben, PPPL, was at MIT this week to work on C-Mod data analysis and to prepare for installation of improved GPI optics. He also gave a talk "Moving Divertor Plates in a Tokamak" at the C-Mod weekly science meeting. Sam Pierson and Steve Wukitch visited our vendor in Huntsville AL to discuss the process for coating of molybdenum tiles (outer divertor shelf, limiter, and RF limiters) and schedule. The first batch of tiles are expected next month. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly